(a) Field of the Invention
The subject invention pertains to the use of moderate-to-low-RPM, twin-screw, rotary gas/air compressor system with continuous, water-evaporation cooling of a gas throughout all or part of it's compression cycle. The compressor system may use an inorganic, water/mineral slurry, or a non-combustible, organic lubricant emulsified into a water base, as an evaporative coolant, and a compression-cavity's partial sealant and lubricant. For compression of air, oxygen, oxygen-enriched air, or other combustion-support gases, sealants or lubricants must be of non-combustible and non-reactive materials. Such materials may consist of a water dispersion of inorganic minerals, like bentonite and related clay minerals, colloidal glacial silt, silica gel, mica, etc., a water dispersion of synthetic, inorganic, spherical particles, acting as micro-ball-bearings, or a non-combustible lubricant, colloidally dispersed or emulsified into a water base. The water in such sealant and lubricating dispersions will undergo continuous and rapid evaporation, and must be replaced by continuous water injection in order to maintain sufficient slurry sealant and lubricant consistency and volume. The compressed outlet gas consists of the inlet gas composition plus the commingled volume of steam created by the evaporation of water used for this continuous evaporative cooling.
The subject gas/air compressor system is designed to compress a moderate-to-high-temperature, moderate-to-high-pressure, thermal-energy carrier fluid (TECF). From the compressor system, the TECF carrier fluid may be transmitted to a series of injection wells and then into underground permeable geologic zones for production of in-situ-retorted-and-hydrocracked products derived from fixed-bed carbon deposits (FBCD), such as oil shale, volatile coal beds, tar sands, heavy-oil deposits, carbonaceous shale, etc., with such products produced through a series of production wells.
The subject gas/air-compressor system may be designed to use saline-water solutions with a controlled rate of increasing dissolved minerals in the evaporating-water solution without leaving any precipitation or scaling deposits within the compressor. Furthermore, the water solutions, with increased-dissolved-mineral content exiting from such a compressor system, can be depressurized in a manner to control the precipitation of mineral salts for possible recovery of valuable mineral by-products.
(b) Discussion of Prior Art
Heretofore, prior gas-compression technology has generally used multiple stages of near adiabatic gas compression with inter-stage coolers to control compressed-gas temperatures. Such inter-stage coolers generally use heat-transfer coils of coolant to provide the transfer of thermal energy of hot, compressed gas through the walls of such coils and into an independent, circulated coolant. However, a water-injection, evaporative-cooling technology can be used in such inter-stage coolers between the near adiabatic compression stages. Also, centrifugal turbine compressors or axial-flow turbine compressors have been commonly used for such near adiabatic-compression stages with inter-stage cooling.
None of the above mentioned, prior-art, compressed-air-and-gas technology specifically uses compression systems with a continuously injected, liquid-water phase to provide internal, water-evaporation cooling in the compression process. If limited-volume, internal-water-evaporation cooling is attempted in centrifugal turbine compressors, or in axial-flow turbine compressors, mineral-salt precipitation and scaling would occur unless very pure mineral water is used.